Your body requires enzyme reactions as catalysts to maintain life. The action of carbonic andydrase, for example, accelerates the movement of carbon dioxide from body cells into the blood by speedily converting carbon dioxide and water into bicarbonate ions, protons and carbonic acid. The blood transports these chemicals to the lungs, where they transform again so carbon dioxide can be released during respiration. Most of the 200 known enzymes are proteins and require a specific substrate that binds to an active site for the necessary chemical reaction to occur.

Enzymes Are Locks

Enzymes work like a lock in the chemical reaction process that's necessary to maintain life. The body contains many enzymes and many substrates, but for life to continue in a healthy manner, the correct enzyme must efficiently locate and unite with its specific substrate. Each enzyme can attract its specific substrate and accelerate the chemical reaction that must occur in the appropriate time span.

Enzymes Sites Are Keyholes

Each enzyme has receptor sites that allow specific substrates to enter and create a chemical reaction product. The enzyme sites work like the keyhole in a lock. Like the lock on a door, only certain keys will fit in the keyholes, and perhaps only one key will open the lock. Put the wrong key into the keyhole, and you can prevent the correct key from unlocking the door.

Substrates Are Keys

Each enzyme will only respond to one or two substrates, which work like keys for the enzyme lock. The molecular structure of the substrate must correspond in size and shape to the receptor site on the enzyme to produce the desired chemical response. When the enzyme locates its appropriate substrate, the substrate enters the receptor site and both the enzyme and substrate transform to create a complete union so the chemical reaction can occur. This modified lock and key model, known as the induced fit theory, also explains why some substrates, known as inhibitors, fit in the enzyme site but don’t create a chemical reaction.

Inhibitors Jam the Lock

Inhibitors work like a key that will enter the keyhole but cannot turn the lock tumblers because the teeth don't match the lock configuration. The inhibitors jam the receptor sites, slowing down or preventing the chemical reaction that would occur if the correct active substrate entered the site. This type of reaction can occur when you take a drug to reduce clotting in the arteries and veins but some empty receptor sites remain available so the appropriate substrate produces blood clotting when you sustain a cut or other wound.

About the Author

Rev. Kathryn Rateliff Barr has taught birth, parenting, vaccinations and alternative medicine classes since 1994. She is a pastoral family counselor and has parented birth, step, adopted and foster children. She holds bachelor's degrees in English and history from Centenary College of Louisiana. Studies include midwifery, naturopathy and other alternative therapies.